Source-Agnostic Time-Domain Directional Relay

Inverter based resources (IBRs) are instrumental in facilitating the integration of renewable energy resources into the power grid. However, IBRs exhibit unique fault characteristics significantly different from synchronous generators (SGs), dictated by their proprietary controls, posing challenges for the reliable operation of directional relays designed in phasor domain. This paper proposes a source-agnostic directional relay formulated in time domain, thus making any polarization unnecessary. It is immune to decaying dc offset and pre-fault currents, and applicable to transmission and distribution feeders with up to 100% IBR penetration. Its performance is documented using PSCAD simulations and shown superior to a numerical commercial relay in a hardware in the loop setup. Its chosen sampling rate of 24 or more samples per cycle (spc) makes it readily implementable in commercial numerical relays.